Fluid valve, in particular a return valve for a painting system

ABSTRACT

Exemplary illustrations of a fluid valve, e.g., a return valve for returning residual paint, rinsing agent, and compressed air from a paint line when changing color in a painting system, are disclosed. An exemplary fluid valve may be adjusted between an open position, in which the fluid valve is at least partially open, e.g., for rinsing a paint line with a rinsing agent and for pressurizing the paint line with a new color for the color change, and a closed position, in which the fluid valve is closed, e.g., for applying the new color after the color change. An exemplary fluid valve may switch to the closed position, upon actuation by the medium thereof, e.g., medium flowing through or present in the valve. In another example, a fluid valve may close depending on the fluid present at the input side.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application is a Continuation of U.S. patent application Ser. No.13/319,156 filed on Jan. 23, 2012, which is a National Stage applicationwhich claims the benefit of International Application No.PCT/EP2010/002763 filed May 5, 2010, which claims priority based onGerman Application No. DE 10 2009 020 064.9, filed May 6, 2009, each ofwhich are hereby incorporated by reference in their entireties.

FIELD

The present disclosure relates to a fluid valve, e.g., a return valve,which serves in a painting system, for example during a color change tolead residual color, flushing agent, color foam, air and/or compressedair from a color line, a loading area, etc. into a return system and/orto stop the color flowing downstream autonomously from flowing away intothe return system.

BACKGROUND

FIG. 13A shows a highly simplified form of a conventional paintingsystem 1 for painting vehicle body parts, wherein the painting system 1comprises as application device a rotary atomizer 2 with a bell cup 3,which produces a spray jet 4 of paint while operating. The rotaryatomizer 2 is hereby supplied with the paint to be applied over a colorline 5, a main needle valve 6 being located in the color line 5 whichguides the flow of paint to the rotary atomizer 2 and which is openedduring a coating process. Furthermore, the painting system 1 is fittedwith a return line 7 in which a return valve 8 is located, wherein thereturn line 7 opens into a return system in order to capture residuesremaining during a color change (for example flushing agent, residualcolor, color foam) and to dispose them economically.

When changing the color in the painting system 1, firstly the mainneedle valve 6 is closed whereby the flow of paint to the rotaryatomizer 2 is interrupted. The return valve 8 is then opened and thecolor line 5 is cleaned using a flushing agent and compressed air(blasts of compressed air), the residues of the paint remaining in thecolor line 5 being led over the opened return valve 8 and through thereturn line 7 into the return system. Subsequently, the color line 5 isloaded (pressurized) with the new paint of the desired color, whereinthe main needle valve 6 is still closed while the return valve 8 isopened. The loading can be stopped when no more color foam or compressedair comes out in the return line 7 downstream behind the return valve 8but fresh color. This is recognized by the painting system 1, in thisexample by a light barrier which consists of a source of light 9 and anoptical sensor 10, wherein the light source 9 and the sensor 10 arelocated on opposite sides of the in this area transparent return line 7so that the light barrier detects the transparency to light of the fluidcoming out behind the return valve 8. During flushing the color line 5,a mixture of flushing agent, residual color and compressed air flowsthrough the return line 7, this mixture being relatively transparent tolight due to the high proportion of air in it. After loading of thecolor line 5, fresh paint appears at the outlet of the return valve 8which contains hardly compressed air and is therefore relativelyimpervious to light. The sensor 10 is connected on the output side witha control unit 11 which closes the return valve 8 if the light barrierdetects that fresh paint appears at the outlet of the return valve 8.

FIG. 13B shows a modification of the painting system 1 according to FIG.13A which is different in that the return line 7 here branches off fromthe color line 5 downstream behind the main needle valve 6.

A disadvantage of the painting system 1 described above is firstly thefact that the return line 7 can get dirty during operation so that thelight barrier can no longer detect the transparency to light of theflowing through fluid.

A further disadvantage of the conventional painting system 1 describedabove is the reaction time between reaction of the optical sensor 10 andclosing the return valve 8, wherein fresh paint is led away over thereturn line 7 during the reaction time which leads to respective lossesof color.

The conventional painting system 1 described above also needs additionalcomponents in the form of the source of light 9 and the optical sensors10 to control the return valve 8, whereby the costs for manufacture andcommissioning and also the fault liability increase.

Furthermore, it is also known from the prior art that return valve 8 canbe actuated during a color change without a light barrier according to aprescribed time program. Here, the assumption is made that during acolor change after a flushing operation, the fresh paint appears at aparticular time in the return line 7 downstream behind the return valve8.

A disadvantage of using this known control for the return valve 8 basedon a time program is the fact that the time required during a colorchange for flushing and subsequent loading of the fresh paint depends onthe viscosity of the paint so that a wrongly adjusted viscosity orfluctuations in the viscosity lead to inaccurate controlling of thereturn valve 8. If the return valve 8 is closed too late then freshpaint will be led over the return line 7 into the return system which isassociated with corresponding losses of color. If, on the other hand,the return valve 8 is closed too early there will still be residues ofthe prior flushing operation in the color line 5 upstream before thereturn line 8 whereby the painting quality would be impaired afteropening the main needle valve 6.

Accordingly, there is a need to appropriately improve on theconventional painting system 1 described above, in particular, with theoption being provided to control the return valve 8 with the leastpossible effort and as precisely as possible when color is changed.

BRIEF DESCRIPTION OF THE FIGURES

While the claims are not limited to the specific illustrations describedherein, an appreciation of various aspects is best gained through adiscussion of various examples thereof. Referring now to the drawings,illustrative examples are shown in detail. Although the drawingsrepresent the exemplary illustrations, the drawings are not necessarilyto scale and certain features may be exaggerated to better illustrateand explain an innovative aspect of an illustration. Further, theexemplary illustrations described herein are not intended to beexhaustive or otherwise limiting or restricting to the precise form andconfiguration shown in the drawings and disclosed in the followingdetailed description. Exemplary illustrations are described in detail byreferring to the drawings as follows:

FIG. 1 is a schematic illustration of a return valve, according to anexemplary illustration, which switches at the end of a loading(pressurizing) process in response to a coating medium present in thevalve, i.e., it's “own medium,” which may actuate the return valve intothe closing position,

FIG. 2 is a modification of the exemplary return valve according to FIG.1, for which the control air is fed through the valve needle forexternally actuated closing of the return valve,

FIG. 3 is a modification of the exemplary return valve according to FIG.1 with a pneumatic closing force amplifier, the closing force amplifierbeing fitted with a slide valve,

FIG. 4 is a modification of the exemplary return valve according to FIG.3 with a different design of the closing force amplifier,

FIG. 5 is a modification of the exemplary return valve according to FIG.1 with just one single control air connection which serves forexternally actuated opening of the return valve,

FIG. 6 is an alternative exemplary illustration of a return valve with amembrane,

FIG. 7 is a modification of the exemplary return valve according to FIG.6 with an additional piston for externally actuated opening of thereturn valve,

FIG. 8 is a further development of the exemplary return valve accordingto FIG. 7, it being also possible to arrange externally actuatedpneumatic closing of the return valve,

FIG. 9 is a modification of the exemplary return valve according to FIG.8, the piston being connected over a compensation element with play withthe shut-off body,

FIG. 10 is a further development of the exemplary return valve accordingto FIG. 9 with a pilot valve for externally actuated closing of thereturn valve,

FIG. 11 is a modification of the exemplary return valve according toFIG. 7, the shut-off body having a perforated disc,

FIGS. 12A-12D are various operating conditions of the return valve,according to one exemplary illustration,

FIG. 13A is a schematic illustration of a conventional painting systemwith a return line,

FIG. 13B is a schematic illustration of another conventional paintingsystem.

FIG. 14A is an enlarged cross-sectional view of a return valve similarto the return valve according to FIG. 9, the drawing showing the returnvalve in the loading (pressurizing) position, according to an exemplaryillustration,

FIG. 14B is the return valve according to FIG. 14A in a closing positionin which the return valve can be set by the color pressure present atthe inlet side and/or actuated by compressed air, according to anexemplary illustration

FIG. 14C is the exemplary return valve according to FIGS. 14A and 14B inan opened flushing position to flush the color line, according to anexemplary illustration,

FIG. 15 is an alternative exemplary illustration of a return valve withclosing force amplification in a loading/waiting position (without coloractuation), according to one exemplary illustration,

FIG. 16 is a perspective view of an arrest element of an arrestmechanism for a return valve according to FIG. 15, according to anexemplary illustration,

FIG. 17A shows the return valve according to FIG. 15 in aclosing/painting position (with color actuation and closing forceamplification), according to an exemplary illustration,

FIG. 17B shows the return valve according to FIG. 15 in a flushingposition (with compressed air support), according to an exemplaryillustration,

FIGS. 18A-18C are detailed views of various exemplary illustrations ofvalve seats, rods or compensation elements and shut-off bodies, and

FIG. 19 shows installation positions of a fluid valve, according to anexemplary illustration.

DETAILED DESCRIPTION

The present disclosure includes the general technical teaching to use afluid valve as return valve which is actuated by “own medium,” i.e., amedium present in or flowing through the valve. In one exemplaryillustration of a fluid valve actuated by an “own medium,” a fluid valveused as a return valve is actuated in dependence on a fluid present atthe inlet side, and may thereby switch to a closing position and/orinfluences the through flow behavior (e.g. the through flow behavior ofa fluid such as (residual color, flushing agent, air and/or compressedair) through the valve. For example, the influenced through flowbehavior can, merely as examples, include the fluid stream, the fluidflow, the fluid throughput, an opening position, a closing positionand/or one or more positions between the opening position and theclosing position. This means that controlling of the valve position isnot achieved externally actuated by a valve drive, but by a property(e.g. viscosity) of the fluid present at the inlet side. This generaltechnical teaching can furthermore also be used, for example, in orderto activate a closing force amplifier, actuated by own medium, dependenton the fluid present at the inlet side, whereby a closing forceamplification can be achieved and activated, respectively.Advantageously, a valve can be provided which can lead a first fluid(e.g. residual color, flushing agent, color foam and air (e.g.compressed air)) from a first line (e.g. a color line) and/or a firstarea (e.g. a loading area) self or own medium actuated into a secondline (e.g. a return system) and/or can prevent a second fluid (e.g.color for the coating operation) self or own medium actuated fromflowing away into the second line.

An exemplary fluid valve may have an opening position in which the fluidvalve is at least partially open, in particular for flushing the colorline with flushing agent and for loading (pressurizing) the color linewith a new color during the color change.

An exemplary fluid valve furthermore may have a closing position inwhich the fluid valve is closed, e.g., for applying the new color afterthe color change.

The fluid valve may be adjustable between the opening position and theclosing position, wherein the adjustment is actuated by the fluidpresent at the inlet side, and in another exemplary illustration, byit's own medium.

As part of the exemplary illustrations, the switching operation from theopening position into the closing position may be actuated by the fluidpresent at the inlet side, e.g., by it's own medium. It is however alsopossible that the switching operations are actuated or achieved in bothdirections by it's own medium. There is thus the possibility as part ofthe exemplary illustrations, that the fluid valve switches are actuatedfrom the closing position into the opening position by it's own medium.

In one exemplary illustration, the fluid valve is a return valve in apainting system, e.g., as described above with regard to the prior art,to lead residual color, flushing agent, color foam and air or compressedair during a color change from the color line into a return system. Inthis example, the return valve m a y differentiate based on itsconstruction between a first medium (e.g., a fluid) and a differentsecond medium (e.g., another fluid), in particular between color on theone hand and air, compressed air, color foam containing air and flushingagent on the other hand, wherein the return valve switches, for example,autonomously and based on its construction into the closing position ifthere is a particular medium, in particular fresh color, on the inletside of the return valve. It is also possible, that the valvedifferentiates based on its construction between a fluid (e.g. flushingagent, (residual) color, etc.) on the one hand and a gaseous medium(e.g. air and compressed air, respectively) on the other hand. Anexemplary return valve, on the other hand, may advantageously switchautonomously and based on its construction into the opening positionand/or remains at least in the opening position if there is air orcompressed air or color foam at the inlet side of the return valve. Thisown medium actuated controlling of the return valve allows dispensing ofan external valve drive and a complex sensory system needed todifferentiate between the fresh paint on the one hand and flushingagent, residual color and air and compressed air, respectively, andcolor foam on the other hand. The exemplary illustrations are not,however, restricted to the exemplary illustrations in which controllingof the fluid valve is exclusively own medium actuated. It is ratherpossible, as part of this the exemplary illustrations, that the ownmedium actuated controlling of the fluid valve can be combined with anexternal control which will be described in detail below.

Furthermore, the own medium actuated control can advantageously be usedfor achieving and activating, respectively, a closing forceamplification. For example the fluid or return valve can be provided toautonomously and based on its construction activate a closing forceamplifier (which will be described in more detail below), if there iscolor, e.g., a coating medium having a predetermine shading or color, atthe inlet side of the fluid or return valve. It is furthermore possibleto provide a fluid or return valve in such a way that it canautonomously and based on its construction activate and/or control anarrest mechanism (which will be described in more detail below), inparticular unlock it, if there is color at the inlet side of the fluidor return valve, whereby a closing force amplification can be achievedand activated, respectively.

In one exemplary illustration, the fluid valve switches due to its ownmedium actuated controlling dependent on the viscosity of the fluidpresent at the inlet side in the closing position. Fresh paint whicharrives at the return valve during loading (pressurizing) may have ahigher viscosity than the air-containing color foam which arises duringflushing the color line, thereby facilitating detection of a change influid viscosity. There is also the possibility, as part of the exemplaryillustrations, that the fluid valve switches between the openingposition and the closing position dependent on other properties of thefluid present at the inlet side. For example the switching process ofthe fluid valve can be controlled by the mass density, the physicalcondition, the pressure expansion, the electrical conductivity, opticalproperties (e.g. permeability to light and color), heat conductivity,vibration behavior, magnetic permeability and/or by the pressure of thefluid present at the inlet side.

In one exemplary illustration, the fluid valve is opened to a maximum inthe opening position so that the color line can be flushed with amaximum amount possible of the flushing agent stream. Furthermore, thefluid valve can have, in addition to the opening position, and theclosing position a waiting position in which the fluid valve is at leastpartially open, for example for waiting for a new color while loadingthe new color. An exemplary fluid valve can be designed in such a waythat it only switches from the waiting position, but not from theopening position, autonomously and by it's own medium actuated into theclosing position, whereas for switching from the opening position anexternal control of the fluid valve is necessary.

With such a constructional design of the fluid valve with threeswitching conditions (opening position, waiting position and closingposition) the fluid valve may, during a color change, be initiallyswitched into the opening position so that the color line can be flushedwith a maximum amount possible of the flushing agent stream as quicklyas possible. At the end of the flushing process and therefore at thebeginning of loading with the new color, the return valve may beswitched from the opening position into the waiting position, and in oneexemplary illustration this switching process may be achieved by anexternal valve control. At the end of the loading process fresh paintfinally appears at the inlet of the return valve whereby the returnvalve is switched, e.g., by being actuated by it's own medium, from thewaiting position into the closing position.

It was mentioned above that the exemplary illustrations are notrestricted to a fluid valve which is exclusively controlled in an ownmedium actuated manner. Rather, the exemplary illustrations also includea fluid valve which is additionally controllable externally by anexternal valve drive, in particular external medium actuated (e.g. bycompressed air).

An exemplary fluid valve may therefore comprise first control input,e.g., a first control air connection over which control air can be fedto switch the fluid valve externally actuated into the closing position.The air and/or compressed air fed over the first control air connectioncan serve here to support the own medium actuated switching action ofthe fluid valve. There is also the possibility, however, that the fluidvalve can be switched over the first control input into the closingposition independently of the fluid present at the inlet side.

Furthermore, in some exemplary illustrations, a fluid valve may comprisea second control input over which the fluid valve can be switchedexternally actuated into the opening position. Also the second controlinput may be a second control air connection over which air and/orcompressed air can be fed to control the fluid valve.

In one exemplary illustration, the fluid valve has a cylinder and apiston movable within the cylinder, wherein the piston is able to move ashut-off body between the closing position and the opening position.Furthermore the fluid valve in this exemplary illustration has a valveseat wherein the shut-off body closes the valve seat in the closingposition, whereas the shut-off body opens and releases, respectively thevalve seat in the opening position. The valve movement may be drivenhere by the piston which can be applied with air or compressed air onone side or on both sides. Furthermore the piston can also be appliedwith a spring force of a spring on one side or on both sides in order toset a desired neutral position.

Furthermore, in some exemplary illustrations the fluid valve cancomprise a closing force amplifier which amplifies the own mediumactuated closing force, for example so that the fluid valve closes asquickly and/or as securely as possible if during loading the fresh colorfresh color appears at the return valve on the inlet side.

The closing force amplifier can, for example, operate external mediumactuated, in particular by air and/or compressed air. It is, however,alternatively also possible that the closing force amplifier operates bymeans of a spring and/or preload mechanism, in particular produces theamplified closing force by the spring and/or a preload mechanism.

It is possible that the closing force amplifier includes an arrestmechanism which, for example, can create an arrest with a bearing orsupport part (e.g. a bearing or stop plate, an abuting ring, etc.)located in the fluid valve. The bearing part may have a central openingand may be provided, for example, to create a bearing portion, supportportion and/or arrest portion at the peripheral edge and/or adjacent tothe central opening. The bearing part may advantageously be fastened ona wall of the cylinder and/or a housing of the fluid or return valve.

In one exemplary illustration, the arrest mechanism is switchable orcontrollable, in particular lockable and/or unlockable. In this example,the arrest mechanism (or the arrest) can be controlled or switched ownmedium actuated dependent on the fluid present at the inlet side, inparticular unlocked, in order to achieve or activate the closing forceamplification and/or in order to achieve the closing position or toallow the fluid or return valve to move into the closing position.

It is thus advantageously possible that the closing force amplifier isactivated by a fluid (e.g. fresh color, paint, etc.) present at thevalve (for example at the shut-off body of the valve) and/or the arrestmechanism is unlocked, in order to achieve a closing force amplificationor to activate it, in particular in that by the unlocking a springand/or preload mechanism (e.g. a coil or pressure spring) is released orrelieved, whereby the shut-off body can be pressed with closing forceamplification against the valve seat.

In one exemplary illustration, the arrest mechanism can be designed as asnap connection mechanism, a latch connection mechanism and/or aclamping connection mechanism.

For a pneumatic closing force amplifier the closing force amplifier maycomprises an amplifier valve which selectively opens or closes the firstcontrol air connection which opens into the cylinder and serves to closethe fluid valve, wherein the closing force amplifier opens the amplifiervalve if the own medium actuated control of the fluid valve leads to aslight closing of the fluid valve, whereupon the support force isinitiated by the first control air connection and amplifies the closingforce.

In one exemplary illustration of the closing force amplifier theamplifier valve is a sliding valve which comprises a valve slider whichis coupled with the piston so that movement of the piston leads to acorresponding movement of the valve slider. The closing force amplifieris designed here in such a way that the valve slider closes the firstcontrol air connection if the piston of the fluid valve is in theopening position. This means that no force amplification acts when thefluid valve is in the opening position. The closing force amplifier is,on the other hand, designed in such a way that the valve slider releasesthe first control air connection if the piston has moved a fraction ofits stroke from the opening position in the direction of the closingposition so that the force amplification acts. During a closing movementof the fluid valve, the closing force support does not act yet in theopening position but only if the piston has moved slightly from theopening position in the direction of the closing position.

There is the option that the first control air connection, which servesto close the fluid valve, opens radially or axially into the lateralsurface of the cylinder.

For an axial opening of the first control air connection in thecylinder, the first control air connection may be directly or indirectlyclosed or opened by the piston, wherein the opening mouth of the firstcontrol air connection has a smaller cross-section than the piston,wherein the ratio of the cross-sections defines the force amplificationfactor. The closing force amplification is based here on the principlethat the air pressure applied to the first control air connection for aclosed opening mouth of the first control air connection only acts on arelatively small area and therefore also only generates a relativelysmall force. After opening the opening mouth of the first control airconnection the air pressure applied to the first control air connectiondoes, on the other hand, act over the whole piston surface which issignificantly larger than the opening mouth of the first control airconnection so that also the closing force acting on the piston isrespectively higher.

Furthermore there is the possibility, as part of the exemplaryillustrations, that the closing force amplifier comprises a pressurecontrolled pilot valve, wherein the pilot valve connects a first controlair line with the first control air connection of the fluid valve sothat the pressure in the first control air line supports the closingmovement of the fluid valve when the pilot valve is opened. The pilotvalve is controlled here dependent on the fluid flowing in the feed lineof the fluid valve. For this purpose, the pilot valve may comprises acontrol input which is connected with the feed line of the fluid valveso that the pilot valve opens when a pressure builds up in the feed lineof the fluid valve at the end of the loading process.

In one exemplary illustration, the fluid valve is formed as a membranevalve and comprises an elastic membrane which carries a shut-off body.The shut-off body of the fluid valve connected with the membrane can beconnected mechanically with a piston as it was already described above.The piston then allows external controlling of the fluid valve into theclosing position and/or into the opening position.

There is also the possibility, as part of the exemplary illustration,that the fluid valve comprises a shut-off body, e.g., with a perforateddisc, wherein slit-shaped holes can be located in the perforated disc.The size of the holes in the perforated disc is arranged in such a waythat a certain closing force is generated dependent on the viscosity ofthe fluid present at the inlet side which leads to closing of the fluidvalve when exceeding a certain viscosity limit.

Alternatively the own medium actuation of an exemplary fluid valve canbe realized by providing only a small ring gap between the shut-off bodyand the surrounding valve seat in the opening position (and the waitingposition, respectively). The gap width of the ring gap is set here insuch a way that a pressure difference arises between the inlet side andthe outlet side of the fluid valve dependent on the viscosity of thefluid flowing through, wherein the pressure difference acts on theshut-off body and generates a closing force.

If, for example, air flows through the fluid valve then the fluid valveonly offers a small flow resistance despite the small ring gap so thatthe pressure difference between the inlet side and the outlet side ofthe fluid valve is low, which leads to a correspondingly small closingforce. In this case the fluid valve remains in the opening position sothat the air or compressed air at the inlet side can flow through nearlyunhindered.

If, on the other hand, there is fresh paint flowing through the fluidvalve then the small ring gap of the fluid valve offers a larger flowresistance due to the higher viscosity of the paint which leads to acorrespondingly higher pressure difference between the inlet side andthe outlet side of the fluid valve. The higher pressure differencebetween the inlet side and the outlet side of the fluid valve in turngenerates a closing force whereby the fluid valve closes autonomouslyand/or the closing force amplification is activated.

Furthermore, in another exemplary illustration a fluid valve cancomprise a position sensor which recognizes in which position the fluidvalve is located (e.g. the opening position, the closing position and/orthe waiting position or the loading position) in order to allowfeedback, wherein the position sensor being able, for example, tooperate pneumatically, electrically or opto-electronically. It is alsopossible that the sensor only queries or detects a particular position,in particular only the closing position.

Furthermore, there is the possibility, as part of the exemplaryillustration, that the shut-off body of the fluid valve is connected bya rod or a mechanical compensation element with the piston, wherein thecompensation element allows a play between the shut-off body and thepiston. The play of the compensation element is may be larger here thanthe movement of the shut-off body from the opening position into theclosing position so that the shut-off body can advantageously move fromthe opening position and/or from the waiting position into the closingposition being actuated by it's own medium and/or without movement ofthe piston.

For this example with a compensation element for connection of thepiston with the shut-off body, there may be an elastic membrane providedwhich moves the shut-off body in the area of play into the openingposition or into the waiting position. The positioning movement of themembrane can take place here based on the own elasticity of the membraneand/or by means of a spring element (for example a coil spring).Furthermore, the membrane can also achieve a sealing function. Forexample, the membrane can be connected by means of a membrane holderwith the rod and the compensation element, respectively.

The arrest mechanism can include an arrest element which is may bedesigned elastically in order to alter its original form when a force isapplied to it, whereby, for example, unlocking, the closing positionand/or the closing force amplification can be achieved and in order toreturn into its original form when the force is no longer applied,whereby, for example, locking, the waiting position, the openingposition and/or a deactivation of the closing force amplification can beachieved.

The arrest element may have a base which is attached to the piston rodand at least one, and in some examples more than one, arrest lever whichprotrudes from the base. The arrest element can, furthermore,advantageously have at least one arrest portion for formation of anarrest. The arrest may be formed between the arrest portion and thebearing or support part (e.g., the bearing portion, support portion orlocking portion of the bearing part and on the circumferential edge ofthe central opening, respectively).

Furthermore, the arrest element can include at least one switchingportion (for example a beveled switching surface) for interaction with aswitching element in order to achieve unlocking and/or locking of thearrest of the arrest portion. The arrest portion and/or the switchingportion may be arranged in the area of the free end of the at least onearrest lever.

The arrest mechanism can further include a switching element (forexample a beveled switching surface) for unlocking and/or locking of thearrest of the arrest portion. The switching element may be connectedwith the rod or the compensation element and/or is movable together withthe rod or the compensation element. The switching element may beprovided on the membrane holder which is located on the rod or thecompensation element, but can, however, also be provided on the rod orthe compensation element.

In one exemplary illustration the switching element and/or the shut-offbody is provided, for example, to move from the waiting position and/orthe opening position axially in the direction of the arrest element (orpiston), in particular urged by the fluid present at the inlet sideand/or by the closing force amplifier in order to achieve the closingposition and/or the closing force amplification and/or in order tounlock the arrest of the arrest portion or to deform the arrest elementfrom its original form, e.g., radially inwards.

Furthermore the switching element and/or the shut-off body may beprovided, for example, to move from the waiting position and/or theclosing position axially away from the arrest element (or piston), inparticular urged externally actuated (for example by air or compressedair) over the second control input in order to achieve the waitingposition and/or the opening position and/or in order to lock the arrestof the arrest portion or to bring back the arrest element into itsoriginal form, e.g., radially outwards.

In one exemplary illustration, the shut-off body may be provided on thefree end of the rod or the compensation element.

The fluid valve can include a valve seat which has at least one conicalportion and at least one cylindrical portion.

Furthermore the fluid valve can include a shut-off body which has atleast one conical portion and at least one cylindrical portion.

It is furthermore possible to seal off the shut-off body using a sealingmeans (for example a sealing ring such as an O-ring, and/or a sealingedge, merely as examples) or to apply a sealing means to it. The conicalportion of the shut-off body may have a circumferential sealing edge orseal ring, in particular, in order to sealingly lay on the conicalportion of the valve seat in the closing position.

The cylindrical portion of the shut-off body may be provided to form anaxially extending ring gap in the waiting position but possibly also inthe opening and/or closing position with the cylindrical portion of thevalve seat, which has a substantially constant gap size or gap widthover its axial extension and/or which runs coaxially and parallel to thepiston rod, the rod and/or the compensation element. In one exemplaryillustration, the diameter of the cylindrical portion of the shut-offbody is greater than the diameter of the rod or the compensation elementand/or smaller than the the diameter of the cylindrical portion of thevalve seat in order to form a ring gap.

In one exemplary illustration the cylindrical portion of the shut-offbody is located at the free end of the shut-off body, whereas theconical portion of the shut-off body can be located, for example,between the rod or the compensation element and the cylindrical portion.

In another exemplary illustration the shut-off body includes a firstconical portion, a second conical portion and a cylindrical portion,wherein the cylindrical portion of the shut-off body is located betweenthe first conical portion and the second conical portion of the shut-offbody, whereas the first conical portion, for example, can be locatedbetween the rod or the compensation element and the cylindrical portionand the second conical portion on the free end of the shut-off body.

The arrest element, the bearing part and/or the membrane holder can bemade out of metal, e.g., stainless steel, in particular hardened steel.

It should also be mentioned that the exemplary illustrations are notrestricted to the fluid valve described above as an individualcomponent. Rather, the exemplary illustrations are also directed to acomplete painting system with an exemplary return valve in order to leadthe paint residues arising during flushing a return line during a colorchange of the painting system over a return line into a return system,from where they can be disposed of economically.

There is also the possibility as part of the exemplary illustrations, tointegrate the own medium actuated loading-stop-function into a mainneedle valve of an atomizer. In this way loading would be possible overthe main needle for atomizers without a return system.

The exemplary illustrations also includes a color changing method withat least one of the following method steps or operating phases:

Painting with feeding the paint over the paint line.

Flushing the paint line over the return valve in the return line.

Flushing the painting components and the main needle duct (main needle,nozzle, air cap or bell cup).

Loading-stop valve is brought into the waiting position. This operatingphase can overlap in time with operating phase c).

Filling (loading) of the color line up to the return valve (loading-stopvalve), wherein the return valve closes automatically if there is paintat its inlet.

Influencing own medium actuated onto the through flow behavior (inparticular of a fluid through the valve, for example dependent on thefluid present at the inlet side).

Furthermore, the exemplary illustrations are also directed to use of anyof the exemplary return valves in a painting system.

The exemplary illustrations in accordance with FIG. 1 partiallycorresponds with the conventional painting system described above shownin FIG. 13 so reference is made to the above description, wherein thesame reference numbers are used for corresponding details to avoidrepetition.

The return valve 8 is fitted here with a cylinder 12 in which a piston13 is movable, the piston 13 being sealed against the inner wall of thecylinder 12 by a seal 14, which allows compressed air controlling of thepiston 13. For this purpose the return valve 8 has two compressed airconnections 15, 16, wherein the compressed air connection 15 opens underthe piston 13 into the cylinder 12 and allows a pneumatic externallyactuated closing of the return valve 8, whereas the compressed airconnection 16 opens above the piston 13 into the cylinder 12 and allowsa pneumatic externally actuated opening of the return valve 8.

Furthermore, the return valve 8 may be fitted with two coil springs 17,18, the upper coil spring 17 being weaker than the lower coil spring 18.

The upper coil spring 18 resets with its upper side on the inner endface of the cylinder 12 and presses axially from above against thepiston 13.

The under coil spring 17 rests with its lower side on a stop plate 26and presses from below axially upwards against the piston 13, the stopplate 26 having a central bore in the middle to pass through a pistonrod 20.

The piston rod 20 may be fitted on its lateral surface with acollar-like driver 27 which impacts against the stop plate 26 from belowand takes the stop plate 26 upwards with it when the piston rod 20 ismoved from the waiting position shown upwards into the closing position.

In the waiting position shown in the drawing the stop plate 26 restswith its lower side on a ring-shaped support 28.

Furthermore, the return valve 8 is fitted with a shut-off body 19 whichis connected over a valve needle 20 with the piston 13 so that themovement of the piston 13 is transferred to the shut-off body 19. Theshut-off body 19 sits here in a valve seat 21, wherein in the openingposition shown in the drawing of the return valve 8 there is a smallring gap between the shut-off body 19 and the valve seat 21.

The ring gap between the shut-off body 19 and the valve seat 21 in thisexemplary illustration is sized such that air or color foam arriving atthe inlet side can pass through substantially unhindered, wherein nopressure difference arises between the inlet side and the outlet side ofthe shut-off body 19.

If, on the other hand, there is higher viscous color on the inlet sideat the return valve 8 then the flow of the paint through the ring gapbetween the shut-off body 19 and the valve seat 21 is hindered due tothe low cross-section of the ring gap, whereby a pressure differencearises between the inlet side and the outlet side of the shut-off body19. This pressure difference between the inlet side and the outlet sideof the shut-off body 19 in turn generates a closing force on theshut-off body 19 so that the shut-off body 19 is moved from the waitingor opening position shown in the drawing upwards into the closingposition and the return valve 8 closes.

Furthermore, the return valve 8 can also be moved externally controlledinto the closing position by applying the control connection 15 withcompressed air.

Furthermore, the return valve 8 can be opened again by applying theupper control connection 16 with compressed air.

The exemplary illustration as shown in FIG. 2 corresponds extensivelywith the above-described exemplary illustration shown in FIG. 1, so thatreference is made to the above description, wherein the same referencenumerals are used for corresponding details to avoid repetition.

One special feature of this exemplary illustration is that the controlconnection 15 for closing the return valve 8 is passed coaxially throughthe valve needle 20.

The exemplary illustration according to FIG. 3 partially correspondswith the above-mentioned exemplary illustration according to FIG. 1 sothat reference is made to the above description, wherein the samereference numerals are used for corresponding details to avoidrepetition.

One special feature of this exemplary illustration is that the returnvalve 8 in this exemplary embodiment is fitted with a closing forceamplifier which amplifies the own medium actuated closing force. Forthis purpose the closing force amplifier has an amplifier valve whichcan selectively open or close the compressed air connection 15. Theamplifier valve may substantially consist of a valve slider 22 which isattached on the outside to the underside of the piston 13 and whichprojects downwards over the opening mouth of the compressed airconnection 15.

In the opening position shown in the drawing of the return valve 8, thevalve slider 22 closes the opening mouth of the compressed airconnection 15 so that the air pressure applied at the compressed airconnection 15 does not act on the piston 13.

If, on the other hand, the shut-off body 19 has moved slightly upwardsfrom the opening position shown in the drawing in the direction of theclosing position due to the own medium actuation then the valve slider22 frees the opening mouth of the compressed air connection 15 whereuponthe compressed air applied at the compressed air connection 15 acts onthe underside of the piston 13 and additionally pushes it upwards in thedirection of the closing position.

The exemplary illustration in accordance with FIG. 4 partiallycorresponds with the exemplary illustration described above shownaccording to FIG. 3 so that reference is made to the above description,wherein the same reference numerals are used for corresponding detailsto avoid repetition.

One special feature of this exemplary illustration is the constructionaldesign of the closing force amplifier. The compressed air connection 15opens from below axially into the cylinder 12, wherein the opening mouthof the compressed air connection 15 in the opening position shown inFIG. 4 is indirectly closed by the piston 13 so that only a relativelysmall force acts on the piston 13 since the opening mouth of thecompressed air connection 15 only has a relatively small cross-section.

If, on the other hand, the piston 13 releases the opening mouth of thecompressed air connection 15 during the beginning closing movement ofthe return valve 18 then the whole underside of the piston 13 suddenlyis applied with pressure provided over the compressed air connection 15whereby a significantly larger closing force arises. The forcetransmission ratio is determined here by the ratio of the cross-sectionsof the opening mouth of the compressed air connection 15 on the one handand the piston 13 on the other.

The exemplary illustration as shown in FIG. 5 corresponds extensivelywith the above-described exemplary illustration illustrated in FIG. 1,so that reference is made to the above description, wherein the samereference numerals are used for corresponding details to avoidrepetition.

One special feature of this exemplary illustration is that thecompressed air connection 15 provided in FIG. 1 is not included.Therefore the exemplary illustration according to FIG. 5 does not allowexternally actuated closing of the return valve 8 so that the closingmovement is exclusively own medium actuated controlled.

FIG. 6 shows a fundamentally different example of a return valve,according to an exemplary illustration, that however also partiallycorresponds with the above described exemplary illustrations, so thatreference is made to the above description, wherein the same referencenumerals are used for corresponding details to avoid repetition.

One special feature of this exemplary illustration is that there is anelastic membrane 23 located in the cylinder 12, the shut-off body 19being connected with the middle of the membrane 23 so that the membrane23 generates an appropriate restoring force dependent on its deflection.

Furthermore, the cylinder 12 may have a compensation hole 24 on itsupper side in order to allow pressure compensation during movement ofthe membrane 23.

The exemplary illustration according to FIG. 7 is a combination of theexemplary illustrations according to FIG. 6 with the previous exemplaryillustrations, so that reference is made to the above description,wherein the same reference numerals are used for corresponding detailsrepetition.

One special feature of this exemplary illustration is that there is alsothe piston 13 as well as the membrane 23 located in the cylinder 12, thevalve needle 20 connecting the shut-off body 19 with the membrane 23 andthe piston 13. Therefore the shut-off body 19 in this case can thus bemoved into the opening position by pressure application in a way whichwas described in detail above in that the compressed air connection 16is applied with appropriate pressure.

The exemplary illustration according to FIG. 8 corresponds extensivelywith the exemplary embodiment according to FIG. 7 so that reference ismade to the above description, wherein the same reference numerals areused for corresponding details to avoid repetition.

One special feature of this exemplary illustration is that additionallyto the compressed air connection 16 for opening the return valve 8 alsothe compressed air connection 15 for closing the return valve 8 isprovided.

The exemplary illustration as shown in FIG. 9 corresponds extensivelywith the above-described exemplary illustration shown in FIG. 8, so thatreference is made to the above description, wherein the same referencenumerals are used for corresponding details to avoid repetition.

One special feature of this exemplary illustration is that the piston 13is not connected rigidly with the membrane 23 and the shut-off body 19but over a mechanical compensation element that allows mechanical play.This means that during the closing movement of the shut-off body 19 onlythe membrane 23 is moved whereas the play of the compensation elementbetween the piston 13 and the membrane 23 prevents the piston 13 fromalso being moved. The play of the compensation element is thereforesomewhat larger than the movement of the shut-off body 19 between theopening position and the closing position.

The exemplary illustration as shown in FIG. 10 corresponds extensivelywith the above-described exemplary illustration shown in FIG. 9, so thatreference is made to the above description, wherein the same referencenumerals are used for corresponding details to avoid repetition.

One special feature of this exemplary illustration is that the undersideof the piston 13 can be applied with compressed air over a pilot valve25 in order to support the closing movement of the return valve 8.Actuation of the pilot valve 25 takes place in this case dependent onthe pressure in the color line 5. The pilot valve 25 is therefore fittedwith a control input which is connected with the color line 5.

If the pressure in the color line 5 increases at the end of the loadingprocess because fresh paint is located in the color line 5 then theincreasing pressure in the color line 5 ensures that the pilot valve 25is opened, whereby the underside of the piston 13 is applied withpressure. In this way the own medium actuated closing force is amplifiedwhich leads to rapid closing of the return valve.

FIG. 11 shows another exemplary illustration of a return valve 8 thatcorresponds extensively with the above described exemplaryillustrations, so that reference is made to the above description,wherein the same reference numerals are used for corresponding detailsrepetition.

One special feature of this exemplary illustration is that the shut-offbody 19 has a perforated disc, wherein the fluid must pass through theholes in the perforated disc.

FIGS. 12A-12D show various operating conditions of the exemplary returnvalves during a color change.

FIG. 12A first shows the position of the return valve 8 during flushingthe color line 5. For this purpose the shut-off body 19 is pushed out ofthe valve seat pneumatically externally actuated in order to open thereturn valve 8. The residues made up of flushing agent, color foam,compressed air and residual air arising during the flushing can then beguided over the return line 7 into the return system.

FIG. 12B, on the other hand, shows the condition of the return valve 8during loading of new color. The return valve 8 is then notpneumatically actuated so that the ball-shaped shut-off body 19 restsloosely in the valve seat and just allows air or color foam to passthrough.

FIG. 12C, on the other hand, shows the condition of the return valve 8at the end of the loading process when the color line 5 is alreadyfilled with fresh paint, which has a relatively high viscosity. Therelatively high viscosity of the flowing in fresh paint results in thereturn valve 8 being closed own medium actuated in that the ball-shapedshut-off body 19 is pushed into its valve seat.

Finally, FIG. 12D shows the condition of the return valve duringsubsequent painting, after the previous loading process was ended. Inthis condition, the ball-shaped shut-off body 19 is pulled pneumaticallyexternally actuated into the valve seat in order to securely close thereturn valve.

The return valve 8 as shown in FIGS. 14A-14C corresponds extensivelywith the return valve illustrated in FIG. 9, so that reference is madeto the above description, wherein the same reference numerals are usedfor corresponding details to avoid repetition.

In the enlarged illustration according to FIGS. 14A-14C one can also seethat the piston rod 20 is hollow and has a central hole. A rod 29 can bemoved axially in this central hole in the piston rod 20, wherein the rod29 is firmly connected with the shut-off body 19 and clamped in acentral opening in the membrane 23.

Furthermore, there may be a coil spring 30 located in the central holeof the piston rod 20 which supports on its upper side on the piston 13and on its lower side on the upper end face of the rod 29. Thus the coilspring 30 and the membrane presses the piston 13 and the rod 29 and,therefore, also the shut-off body 19 axially apart. It is also possible,however, that just the membrane takes on the restoring function withoutthe coil spring 30.

Furthermore, it should also be mentioned that there may be a ring-shapedcircumferential, collar-shaped, stop 31 formed at the lower end of thepiston rod 20 in order to limit the movement of the piston 13 upwards(it is not the movement of the piston 13 which is limited but ratherthat of the “package” lying between the piston 13 and a stop plate 32).To do this the return valve 8 is fitted with the stop plate 32, whereinthe stop plate 32 has a central opening through which the piston rod 20is led.

In the loading position according to FIG. 14A and in the closingposition according to FIG. 14B the stop 31 lies with its upper side onthe circumferential edge of the central opening in the stop plate 32 sothat the piston 13 can not move any further upwards.

In the flushing position according to FIG. 14C the piston 13 with thepiston rod 20 is, on the other hand, moved downwards so that the stop 31does not lie on the stop plate 32. The stop 31 lies on the valve bottomin order to limit the valve movement downwards. In this position thestop plate 32 should lie on the valve bottom.

It is furthermore clear to see from the enlarged drawings according tothe FIGS. 14A-14C that there is an elongated hole in the rod 29 in whicha drive pin 33 engages which is connected to the piston rod 20. Thegeometry of the drive pin 33 and the elongated hole are matched witheach other here in such a way that the elongated hole in the rod 29offers mechanical play for the drive pin 33 so that the piston rod 20and the piston 13 on the one hand and the rod 29 and the shut-off body19 on the other hand have axial play.

In the following there will now be described the loading position of thereturn valve 8 shown in FIG. 14A. The loading position of the returnvalve 8 is set during a color change if the color line 5 was flushed andthe color line 5 should be loaded with a new color up to the main needlevalve 6.

In this loading position there is no control air being applied to thecompressed air connection 15 and the compressed air connection 16, inorder to actuate the piston 13. The position of the return valve 8 isthen only determined by the interaction between the elastic membrane 23and the coil springs 17, 18 and 30. Thus the membrane 23 places the rod29 and thus also the shut-off body 19 in the neutral position shown inthe drawing in which there is a ring gap between the shut-off body 19and the valve seat 21 which allows that air initially fed over the colorline 5 can escape over the return line.

The coil spring 17, on the other hand, presses the piston 13 andtherefore also the piston rod 20 upwards until the stop 31 touches thestop plate 32.

Finally the coil spring 30 pushes the rod 29 axially opposite the piston13 downwards.

In the following there will now be described the closing position of thereturn valve 8 shown in FIG. 14B, wherein the return valve 8 can bebrought into the closing position selectively by the color pressurepresent at the inlet side or actuated by compressed air.

In the following there will first be described how the return valve 8 isbrought during loading from the loading position shown in FIG. 14A intothe closing position according to FIG. 14B due to color pressure presentat the inlet side.

If during loading the new color not only air or color foam is fed overthe paint line 5 but fresh color then the higher viscosity of the freshcolor leads to a higher pressure on the shut-off body 19, which ispressed upwards against the elastic restoring force of the membrane 23.Here the mechanical play between the piston rod 20 and the rod 29 allowsthe piston 13 to remain in the same position as in the loading positionshown in FIG. 14A.

FIG. 14C finally shows a flushing position of the return valve 8 inwhich the return valve 8 is opened independently of the fluid pressurepresent at the inlet side in order to allow the color line 5 to beflushed over the return line 7.

For this purpose the piston 13 is applied with compressed air over thecompressed air connection 16 whereby the piston 13 is pressed axiallydownwards. The movement of the piston 13 in this case exceeds themechanical play between the elongated hole in the rod 29 and the drivepin 33 in the piston rod 20. This results in the piston 13 with thepiston rod 20 pushing the rod 29, and therefore also the shut-off body19, downwards. The shut-off body 19 is thereby pushed out of the valveseat 21 whereby the return valve 8 opens.

FIG. 15 shows in turn another exemplary illustration of a return valveof the invention that also partially corresponds with the the exemplaryillustrations described above so that reference is made to the abovedescription, wherein the same reference numerals are used forcorresponding details to avoid repetition.

One special feature of this exemplary illustration includes, amongstother things, closing force amplification by means of an arrestmechanism. In particular, a closing force amplifier can be activated ownmedium actuated dependent on the fluid present at the inlet side inorder to achieve the closing force amplification, e.g., in that thearrest mechanism is unlocked own medium actuated dependent on the fluidpresent at the inlet side in order to achieve the closing forceamplification and/or in order to allow the fluid valve to assume theclosing position.

FIG. 15, in particular, shows in this respect that an arrest element 34is arranged on the piston rod 20. Arrest element 34 includes acylindrical base 35 a which may be fastened coaxially on the piston rod20 and, in one example, four locking levers 35 b which protrude from thebase 35 a (FIG. 16). Each of the locking levers 35 b has a switchingportion, e.g., a beveled switching surface 36, and an arrest portion,e.g., a locking surface 37. The arrest portions 37 are intended toproduce a lockable and unlockable arrest with a bearing part, stop partand/or support part 40.

The switching portions 36 are intended to cooperate with a switchingelement 39, whereby an unlocking and/or locking of the arrest can beachieved between the arrest portions 37 and the bearing part 40. Theswitching element 39 is therefore intended to cooperate with theswitching portions 36 for unlocking and/or locking the arrest betweenthe arrest portions 37 and the bearing part 40, in particular to moveinto engagement and out of engagement. The switching element 39 isconnected with the compensation element and/or the rod 29. Inparticular, the switching element 39 is provided on a membrane holder 38which is located on the compensation element or the rod 29. Theswitching element 39 may comprise a circumferential beveled switchingsurface which is located coaxially to the compensation element or therod 29 and which is provided for interacting with the respective beveledswitching surfaces of the switching portions 36. The 30 switchingelement 39 is provided to move together with the rod 29 or thecompensation element and/or the shut-off body 19.

In particular, the arrest element 34 may be formed elastically by meansof the protruding locking levers 35 b in order to form a switchable(lockable/unlockable) snap, latch and/or clamping connection with thebearing part 40.

As can be further seen in FIG. 15, the bearing part 40 may have acentral opening in the middle to pass through the arrest element 34 (inparticular the locking levers 35 b and/or the arrest portions 37), thepiston rod 20 and/or the rod 29 or the compensation element. The bearingpart 40 is furthermore fastened to an inner side of a wall of cylinder12 or a housing wall of the fluid valve 8. The bearing part 40 may beprovided so that the coil spring 17 can rest on the bearing part 40 withits lower side (in particular on the piston side, that is axially abovein FIG. 15) and can push from below axially upwards against the piston13 and/or to provide a bearing portion, support portion or arrestportion for the arrest portions 37 around the circumferential edge oradjacent to the central opening (on the shut-off body side, that isaxially below in FIG. 15). The bearing part 40 can advantageously bestructurally and/or functionally designed to be similar or evenessentially identical to the stop plate 32. The bearing part 40 may bepositioned between the membrane 23 and the coil spring 17 and/or thepiston 13.

In general the closing force amplifier and/or the arrest mechanismaccording to FIG. 15 functions as follows: During loading of color,valve 8 is pneumatically pressureless in the loading or waitingposition. The shut-off body 19 creates a small ring gap 50 to the valveseat 21. The arriving color displaces the air and the remainingair/flushing agent aerosol from the color ducts (from the color changerto the atomizer) through the loading gap 50 of the (paint stop) valveinto the return line 7. Upon arrival of the color the shut-off body 19is initiated to close by the stiffer color (without control sensorsystem and generally immediately). For secure operation during painting,upon arrival of the color at the shut-off body 19 the arrest mechanismis unlocked, whereby the spring-actuated closing force amplification isachieved, e.g., generated by the coil spring 17 which is located betweenthe bearing part 40 and the piston 13.

During subsequent loading, the compensation element or the rod 29 ismoved by the arriving color in FIG. 15 upwards. In this process theswitching element 39, which is may be located on the membrane holder 38,moves the arrest levers 35 b over the switching portions 36 radiallyinwards.

During the disengaging or unlocking of the arrest levers 35 b or thearrest portions 37 from the bearing part 40, the coil spring 17 isrelaxed and thereby the shut-off body 19 is pressed onto the valve seat21 in a sealing manner.

FIG. 16 shows the arrest element 35 enlarged. The arrest element 35comprises the cylindrical base 35 a and the four arrest levers 35 bprojecting from it. Each of the arrest levers 35 b has the switchingportion 36 and the arrest portion 37.

FIG. 15 shows a cross-section of the return valve in a loading/waitingposition (without actuation by color). The piston 13 is pressed upwardsby the coil spring 17. The movement is, however, limited by the arrestlevers 35 b which are engaged by the arrest portions 37 with the bearingpart 40 (locked). The arrest portions 37 therefore create an arrest withthe bearing part 40, in particular with the circumferential edge of thecentral opening in the bearing part 40.

The drive pin 33 is positioned at the upper end of the elongated hole bymeans of the membrane or additionally by the coil spring 17. Theshut-off body 19 is positioned in such a way that a loading or ring gap50 is created between the valve seat 21 and the shut-off body 19.

FIG. 17A shows a cross-sectional view of the return valve from FIG. 15in a closing position (with actuation by color) or a painting positionwith closing force amplification. The switching element 39 on themembrane holder 38 is initially moved upwards by means of color fed overthe color line 5. In this way the switching element 39 engages with theswitching portions 36 of the arrest levers 35 b in such way that thearrest levers 35 b are pressed radially inwards PR, whereby the arrestbetween the arrest levers 35 b, in particular the arrest portions 37,and the bearing part 40 is unlocked or released. In this way the piston13 can be pushed upwards by the coil spring 17. The shut-off body 19 isinitially impinged upwards by the color fed over the color line 5 andthen more strongly impinged upwards by the closing force amplifier whichgenerates the increased closing force by means of the coil spring 17 inorder to advantageously achieve a tight and secure seal. The drive pin33 is positioned at the lower end of the elongated hole by the colorpressure.

It can, in particular, be seen through making a comparison of FIGS. 15and 17A that the switching element 39 is provided to move from thewaiting/loading position (FIG. 15) axially PA in the direction of thearrest element 34 in order to achieve the closing position (FIG. 17A)and/or the closing force amplification and/or in order to unlock thearrest of the arrest portions 37 with the bearing part 40, in particularin that the arrest element 34 is deformed radially inwards from itsoriginal form (FIG. 16).

FIG. 17B shows a cross-sectional view of the return valve from FIG. 15in a flushing position with compressed air support. The drive pin 33 ispositioned at the upper end of the elongated hole. The piston 13 ispressed downwards by the compressed air fed over the compressed airconnection 16. Furthermore the coil spring 17 is pressed together.Moreover, the shut-off body 19 is moved downwards whereby a flushing gap51 is created between the shut-off body 19 and the valve seat 21. Thearrest portions 37 do not create any arrest with the bearing part 40 inthe flushing position, and are therefore not engaged with the bearingpart 40. The arrest portions 37 are, in particular, spaced away from thebearing part 40 or displaced beyond the engaging position.

It can, in particular, be seen through making a comparison of FIGS. 15,17A and 17B that the switching element 39 is provided to move from theclosing position (FIG. 17A) and/or the waiting/loading position (FIG.15) axially in the direction away from the arrest element 34 in order toachieve the waiting/loading position (FIG. 15) and/or the openingposition (FIG. 17B) and/or in order to create or lock the arrest of thearrest portions 37 with the bearing part 40, in particular in that thearrest element 34 can return to its original form (see FIG. 16).

FIGS. 18A-18C show detailed views of various illustrations of valveseats, rods or compensation elements and shut-off bodies according toexemplary illustrations which partially correspond with the exemplaryillustrations described above and can be provided for the valvesdescribed above so that reference is made to the above descriptions,wherein the same reference numerals are used for corresponding detailsto avoid repetition.

FIG. 18A shows a schematic enlarged view of an exemplary illustration inaccordance with the axial gap principle, in particular of a modified rod29 (or compensation element) and/or a modified shut-off body 19 in thearea of the valve seat 21. The shut- off body 19 is shaped conically,e.g., widening towards the color line 5. Furthermore, the valve seat 21includes a conical portion, e.g., widening towards the color line 5. Theshut-off body 19 is at least partially located in the conical portion ofthe valve seat 21. The shut-off body 19 includes a circumferentialsealing edge 19 x. The circumferential sealing edge 19 x lies in theclosing position sealingly on the conical portion of the valve seat 21,wherein in the flushing and/or waiting/loading position, a loading orring gap 50 is created between the sealing edge 19 x and the conicalportion of the valve seat 21. The sealing edge 19 x shown in FIG. 18A islocated at the free end of the shut-off body 19.

FIG. 18B shows a schematic enlarged view of an exemplary illustration inaccordance with the radial gap principle, in particular another modifiedrod 29 (or compensation element) and/or another modified shut-off body19 in the area of the valve seat 21. The shut-off body 19 comprises afirst conical portion 19 a, a second conical portion 19 b and acylindrical portion 19 c, which is located between the first and thesecond conical portion 19 a, 19 b. The first conical portion 19 aextends from the rod 29 or the compensation element to the cylindricalportion 19 c, wherein the second conical portion 19 b is located at thefree end of the shut-off body 19. The first and second conical portion19 a, 19 b widens respectively, e.g., towards the color line 5. Thevalve seat 21 comprises a cylindrical portion and a conical portionwhich may widen to the color line 5. The conical portion of the valveseat 21 is located at the free end of the valve seat 21, wherein thecylindrical portion of the valve seat 21 in FIG. 18B is locatedcoaxially immediately above the conical portion of the valve seat 21.The diameter of the cylindrical portion 19 c of the shut-off body 19 islarger than the diameter of the rod 29 or the compensation element. Thecylindrical portion 19 c of the shut-off body 19 is provided to form anaxially extending ring gap 60 with the cylindrical portion of the valveseat 21 which has a substantially constant gap size or a constant gapwidth over its axial extension “a”. The axially extending ring gap 60may run coaxially and parallel to the piston rod 20, the rod 29 or thecompensation element. The sealing edge 19 x shown in FIG. 18B is locatedat the free end of the shut-off body 19.

FIG. 18C shows a schematic enlarged view of an illustration inaccordance with the radial gap principle, in particular another modifiedrod 29 (or compensation element) and/or another modified shut-off body19 in the area of a modified valve seat 21. The shut-off body 19includes a conical portion 19 a and a cylindrical portion 19 c. Theconical portion 19 a is located between the rod 29 or the compensationelement and 30 the cylindrical portion 19 c, wherein the cylindricalportion 19 c of the shut-off body 19 is located at the free end of theshut-off body 19. The conical portion 19 a widens, e.g., towards thecolor line 5. The diameter of the cylindrical portion 19 c of theshut-off body 19 is larger than the diameter of the rod 29. Furthermore,the valve seat 21 comprises a cylindrical portion and a conical portionwhich may widen towards the color line 5. The cylindrical portion of thevalve seat 21 is located at the free end of the valve seat 21, whereinthe conical portion of the valve seat 21 in FIG. 18C is locatedcoaxially immediately above the cylindrical portion of the valve seat21. The shut-off body 19 includes a circumferential sealing edge 19 x.The circumferential sealing edge 19 x lies in the closing positionsealingly on the conical portion of the valve seat 21.

The cylindrical portion 19 c of the shut-off body 19 is provided to forman axially extending ring gap 60 with the cylindrical portion of thevalve seat 21 which has a substantially constant gap size or a constantgap width over its axial extension “a”. The axially extending ring gap60 may run coaxially and parallel to the piston rod 20, and/or the rod29 or the compensation element. The sealing edge 19 x shown in FIG. 18Cis located axially behind the free end of the shut-off body 19.

In comparison with the illustration shown in FIG. 18A, the illustrationsshown in FIGS. 18B and 18C may be more advantageous for certainapplications since they generally provide better color pressureconditions. With the illustration shown in FIG. 18A it is possible thata part of the color pressure can also build up behind the shut-off body,thereby reducing the force for closing during a loading process.

In the case of the illustration according to FIG. 18B and, inparticular, the illustration according to FIG. 18C, length tolerances ofthe valve components can be better compensated for by the longer way ofthe rod during a closing process with a constant gap size during thisclosing stroke (the advantage: a large rod and shut-off valve stroke,respectively, easier compliance with manufacturing tolerances). Based onthe longer closing stroke it is also possible to achieve a secure andimproved closing of the exemplary illustrations having a closing forceamplifier.

An exemplary fluid valve for reduction of color losses, in particularfor reduction of color loading losses after a color change, can be usedadvantageously at various positions. As shown in FIG. 19 for example ina color changer FW (see RF2 position), in a metering pump DP (e.g.instead of the position of the bypass valve BV), in an atomizer Z (seeRF1 position), loading of special color supply systems and furtherapplications, etc. Furthermore, the fluid or paint stop valve can beused in a pig station. The fluid or paint stop valve can, e.g., be used(in particular always) for bleeding color or coating agent channelsduring the loading of color and automatic closing upon arrival with thegoal of reducing color losses or at best to avoid them. Furthermore,there is a multiplicity of other possible uses.

The exemplary illustrations are not limited to the previously describedexamples. Rather, a plurality of variants and modifications arepossible, which also make use of the ideas of the exemplaryillustrations and therefore fall within the protective scope.Furthermore the exemplary illustrations also include other usefulfeatures, e.g., as described in the subject-matter of the dependentclaims independently of the features of the other claims.

References in the specification to “one example,” “an example,” “oneembodiment,” or “an embodiment” means that a particular feature,structure, or characteristic described in connection with the example isincluded in at least one example. The phrase “in one example” in variousplaces in the specification does not necessarily refer to the sameexample each time it appears.

With regard to the processes, systems, methods, heuristics, etc.described herein, it should be understood that, although the steps ofsuch processes, etc. Have been described as occurring according to acertain ordered sequence, such processes could be practiced with thedescribed steps performed in an order other than the order describedherein. It further should be understood that certain steps could beperformed simultaneously, that other steps could be added, or thatcertain steps described herein could be omitted. In other words, thedescriptions of processes herein are provided for the purpose ofillustrating certain embodiments, and should in no way be construed soas to limit the claimed invention.

Accordingly, it is to be understood that the above description isintended to be illustrative and not restrictive. Many embodiments andapplications other than the examples provided would be evident uponreading the above description. The scope of the invention should bedetermined, not with reference to the above, description, but shouldinstead be determined with reference to the appended claims, along withthe full scope of equivalents to which such claims are entitled. It isanticipated and intended that future developments will occur in the artsdiscussed herein, and that the disclosed systems and methods will beincorporated into such future embodiments. In sum, it should beunderstood that the invention is capable of modification and variationand is limited only by the following claims.

All terms used in the claims are intended to be given in their broadestreasonable constructions and their ordinary meanings as understood bythose skilled in the art unless an explicit indication to the contraryis made herein. In particular, use of the singular articles such as “a,”“the,” “the,” etc. should be read to recite one or more of the indicatedelements unless a claim recites an explicit limitation to the contrary.

LIST OF REFERENCE NUMERALS

1 Painting system2 Rotary atomizer

3 Bell cup 4 Spray jet

5 Paint line6 Main needle valve7 Return line8 Return valve9 Light source

10 Sensor

11 Control unit

12 Cylinder 13 Piston 14 Gasket

15 Compressed air connection16 Compressed air connection17 Coil spring18 Coil spring19 Shut-off body20 Valve needle and/or piston rod21 Valve seat22 Valve slider

23 Membrane

24 Compensation hole25 Pilot valve26 Stop plate

27 Driver 28 Support 29 Rod

30 Coil spring

31 Stop

32 Stop plate

33 Drive pin

34 Arrest element

35 a Base

35 b Arrest levers36 Switching portion37 Arrest portion38 Membrane holder39 Switching element40 Bearing part, support part and/or stop part50, 60 Ring/loading gap (waiting/loading position)51 Ring gap (open/flushing position)19 a, 19 b Conical portion of the shut-off body19 c Cylindrical portion of the shut-off body19 x Circumferential sealing edge of the shut-off bodyFW Color changerDP Metering pumpBV Bypass valveRF Return systemHV Main needle valveZ Atomizer

1. A fluid valve (8), in particular a return valve (8) for returningresidual color, flushing agent, air and/or compressed air from a colorline (5) during a color change in a painting system (1), in particularduring loading o f a new color during a color change, with a. an openingposition in which the fluid valve (8) is at least partially open, inparticular for flushing the color line (5) with flushing agent and forloading the color line (5) with new color during the color change, andb. a closing position in which the fluid valve (8) is closed, inparticular for applying the new color after the color change, c. whereinthe fluid valve (8) is adjustable between the opening position and theclosing position, characterized in that d. the fluid valve (8) switchesdependent on the fluid present on the inlet side own medium actuated tothe closing position and/or influences the through flow behaviordependent on the fluid present on the inlet side own medium actuated.2-28. (canceled)